Just remember. This does NOT mean that a player tested positive or that he is sick. It means that either he tested positive OR he has come into contact with a person who tested positive. Who knows what it is in this instance. It's not great news but it's not like that player is injured. He'll be able to participate in everything remotely. And then return after some number of days (in quarantine and then having a negative test).
This is going to happen scores of times over not just throughout training camp but also the entire season. So it'll do no good to get very frustrated or upset about it.